This may be my subsonic load
After some disappointing attempts to load this round, I think I finally cooked up the correct subsonic load for my barrel lengths.
Sierra SMK HPBT 220 grain
IMR 4227 powder; 10.5 grain
.223rem brass cut and formed, sized and trimmed to 1.358"
Overall length seated to 2.190", with a light taper crimp.
I'm pulling an average velocity of 1007-FPS with a 16" barrel. 887-FPS with a 10.5" barrel. Obviously, this is a Subsonic load. Not good for general hunting as the Sierra SMK bullet may not expand very well. Although it's a hollow point, it's really designed for target shooting.
I had some problems with failure to feed with some of my loads I did to test velocities. Turns out that I had some crappy PMP South African brass mixed in with my Federal, Remington, PMC, and Fioochi brass. It tooks some time to filter out those crappy PMP rounds, as I had prepped over 1,200 rounds of brass.
Although the original load data had the overall length at 2.600", it had issues feeding from my Magpul Pmags. I think this length was originally set for Thompson Contender barrels and the lengths were originally for the 300 Whisper. The recent data I found has the case length at 2.190" so it does feed better.
Now that my subsonic load is finished, I need to work a load for hunting. I am considering the Hornady A-Max 110 grain and Speer TNT JHP 125 grain. Both are the most price conscience (under .25cent per projectile), and readily available in most stores. Any thoughts on this?
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